 
   Example:
   (batch-get-item cred
-    {:users {:key-name \"names\"
+    {:users {:key-name :names
              :keys [\"alice\" \"bob\"]}
-     :posts {:key-name \"id\"
+     :posts {:key-name :id
              :keys [1 2 3]
-             :attrs [\"timestamp\" \"subject\"]
+             :attrs [:timestamp :subject]
              :consistent true}})"
   [creds requests]
   (as-map

       (.setReturnValues (utils/enum return))))))

(defn update-item
  "Updates an item in a table by its hash key, {attr match-value}.
  See `put-item` for option docs."
  [creds table hash-key update-map & [{:keys [return expected]
                                       :or   {return :none}}]]

    :hash-key   - (required) {:name _ :type #{:s :n :ss :ns :b :bs}}.
    :range-key  - (optional) {:name _ :type #{:s :n :ss :ns :b :bs}}.
    :indexes    - (optional) [{:name _ :range-key _
                               :projection #{:all :keys-only [:attr1 ...]}}]"
  [creds {table-name :name
          :keys [throughput hash-key range-key indexes]
          :or   {throughput {:read 1 :write 1}}}]
